Leviathan

Westerfeld, S. (2009). Leviathan. NY: Simon Pulse. 

Leviathan is a science fiction story set in World War I time frame.  Darwinists, who use fabricated animals such as the Leviathan set after a whale as weapons battle the Clankers who use steam fueled machines. The story revolves around Alek, a prince who is not considered royalty because his mother was a commoner and Deryn, a girl who disguises herself as a boy in order to be part of the British Airforce. When Deryn is shot down, Alek risks his chances of being captured to save her and her crewmates. A battle between the 2 sides ensues, but Alek convinces them to work together to fix the Leviathan in order to escape.  
I would recommend this book to students 13 and older.  Those students
who enjoy history and/or scifi will enjoy this book. 
I enjoyed Deryn's character. She did not bow to the conformity of a woman's place,
she wanted to become a pilot and succeeded.